12 members were present at a board meeting. Each member shake hands with all of the other members before and after the meeting .How many hand shakes were there?
130
134
132
135
Explanation:
In order to have a hand shake there must be two members. Therefore to select 2 out of 12 we have 12C2.
This happens twice that is before and after the meeting
Answer = 12C2 × 2 = 132.